3x3y3z cargo would have few problems being transported through slightly bigger interiors ways.
- Edge and corner blocks contain USD docking and Wedgets/Corners.
- With core, thruster and power it can have 3-4 storage-blocks accessible from the sides depending whether the core takes up one side-face's centre.
3x3y5z is rotate-able and fits into smaller ships (fighter, shuttle, escape-jumper maybe) but could have a hard time navigating around edges in the interior space.
- When you fly the container like a basic ship.
- Or have rails in the bigger hallways of your ship.
- With core, 2-3 thruster and 1 power it can have 1..3 storage blocks linked to 3 crates.
5x5y5z = 125 blocks with 27 blocks covered if you want to hide crates at all costs.
5x5y7z = 175 blocks with 45 blocks covered.
- Far superior to 5x5y5z, still small enough to fit nearly everywhere, but inefficient space usage.
5x5y10z = 250 blocks with 72 blocks covered
- Far superior to 5x5y7z, but they can be difficult to get around edges inside tight transportation tubes due to their length.
11x9y15z = 1485 blocks with 819 covered.
- The first sizes with an acceptable ratio of covered blocks compared to investment into casing, core, thrusters+power (self-moving cargo), rails, storage.